WCAG 2.2: Perceivable

1. Overview

WCAG 2.2 has four principles, remembered as POUR. Content must be Perceivable, Operable, Understandable and Robust. Principle 1 is the one most people picture when they hear "accessibility". A screen reader user needs text where there is an image. A deaf user needs captions where there is speech. A user with low vision needs enough contrast to read. The principle is broad on purpose. It covers every way a person might take information in, not just sight.

Principle 1 contains four guidelines. At Levels A and AA, it has twenty success criteria. Guideline 1.1 has one criterion, 1.2 has five, 1.3 has five and 1.4 has nine. Each criterion is a testable statement. A page either satisfies it or does not. If a page has no video, it satisfies the video criteria automatically. That is why EN 301 549 and WCAG both say a criterion "does not evaluate to false" when the content it governs is absent.

In EN 301 549 the numbering mirrors WCAG. Clause 9.1.4.3 is WCAG 1.4.3 applied to a web page. Clause 11.1.4.3 is the same requirement applied to a native app. So once you know the WCAG number, you can find the European requirement for any kind of ICT.